1. Field of the Invention
The present invention relates to a circuit breaker, and particularly, to a circuit breaker capable of interrupting a circuit in the occurrence of an over-current or an abnormal current.
2. Background of the Invention
Generally, a circuit breaker is installed in a distribution board among distribution equipment such as factories and buildings. In no load state, the circuit breaker serves as a switching apparatus for supplying power to a load side or interrupting power supplied to the load side. In a load state, the circuit breaker serves as a breaker for interrupting power supplied to a load side from a power side in the occurrence of an over-current on a circuit.
The circuit breaker is configured to have variable structures due to a difference of a frame size, the number of poles, an operation manner, etc. Generally, the circuit breaker includes basic components such as a mold case, a contactor, a trip mechanism, a switching mechanism extinguishing device, a terminal, etc.
FIG. 1 is a perspective view of a circuit breaker in accordance with the conventional art, FIG. 2 is a disassembled perspective view of the circuit breaker of FIG. 1, FIG. 3 is an enlargement view of a switching mechanism, and FIGS. 4A and 4B are schematic views for explaining an operation of the switching mechanism.
In an ‘on’ state of a circuit breaker implemented by using a switching handle 15, the circuit breaker may be tripped by a trip button 3 as follows. As shown in the arrow of FIG. 4A, a head portion of the trip button 3 is pressed. Then, the trip button 3 penetratingly-installed at an installation hole 2 of an auxiliary cover 5 is lowered, thereby pressing an inclined side 7a of a bracket 7 of the switching mechanism.
As a result, the bracket 7 hinge-coupled to a load side end of a side plate 8 is clockwise rotated about a hinge shaft 6a, thereby being in a state shown in FIG. 4B. A latch 10 held by a latch holder 9 is released by a restoration force of a main spring (not shown), and is counterclockwise rotated about a rotation center 12. This causes a movable contactor 13 installed at a main shaft 16 to be separated from a fixed contactor 14 by interwork of a link mechanism. As a result, the circuit breaker is tripped.
The circuit breaker is provided with an external device at a body. The external device may include an auxiliary device such as an auxiliary switch or an alarm switch, an under voltage trip device (UVT) which operates when a voltage of a circuit becomes low, a shunt trip coil for remotely tripping the circuit breaker, etc.
The external devices should be mounted to the circuit breaker in an ‘off’ state or a trip state. If a user performs an operation to mount the external device to the circuit breaker in an ‘on’ state by mistake, accidents may occur and the bracket may be damaged due to interference between a mechanical part of the bracket and the external device.